I am bothered by the automatic transmission on my 2012 BMW 5. I bought the car used and although I serviced the transmission, I do not like the way it shifts.
When transmission is cold the 1-2-3 shifts make the car slow down and then lunge, they are not smooth. After a few miles of driving, the shifts are smooth, but only when in Drive mode. If I manually upshift, even at the same rpm as it's done automatically in the Drive mode the hard shift is felt again. And it's stronger as I shift at a higher rpm. 1st to 2nd gear has the hardest shifts. No errors present in INPA.
Has anyone been facing this issue?
ZF 8HP transmission hard shifting 1-2 when cold
- Thread starter cristiancc
- Start date
How many miles? You're looking at a valve body replacement.
Originally Posted By: rooflessVW
How many miles? You're looking at a valve body replacement.
The car is 110k miles. Replaced oil was dark-green but not burnt. Used ZF lifeguard 8 and new pan&filter. I did a software update at the end of 2016.
There is a difference in shift quality some minutes after the engine oil has reached the operating temperature (seeing in the dashboard). This is probably when the transmission oil gets to the right temperature.
But why would it shift bad when the oil is cold and shift better when hot?
In the winter at freezing temps, the 1-2 shifts in the first miles were violent. No sound, just the car reducing speed and then being thrown forward. The 2-3 shifts were better, 3-4 even better to unnoticeable.
Originally Posted By: SteveSRT8
Originally Posted By: rooflessVW
How many miles? You're looking at a valve body replacement.
That's the only automatic trans fluid Bavarian Autosport sells for this car, so it should be correct (Dex VI low viscosity type fluid).
Did the car shift ok before you changed fluid or changed the program?
Fluid at normal operating temps usually give smoother shifts as the temps are optimized for the clutches. Same concept with a manual trans synchronizers. Those shift lousy when cold because the viscosity is still too high for efficient synchronizer operation. Shift at high rpm cold will certainly help shorten the life of your auto trans clutches or manual trans synchronizers. When the fluid gets too hot from hard driving, shift quality can diminish again as the viscosity can get too thin.
Originally Posted By: cristiancc
I am bothered by the automatic transmission on my 2012 BMW 5. I bought the car used and although I serviced the transmission......
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I have a ram 1500 with an 8 speed zf trans. Takees my truck about a mile, or 10 minutes to warm up and shift smoothly. I generally take it easy until trans warms up. Also similar with wife's jeep Cherokee with the ,9 speed trans.
Originally Posted By: rooflessVW
How many miles? You're looking at a valve body replacement.
Originally Posted By: nascarnation
Originally Posted By: rooflessVW
How many miles? You're looking at a valve body replacement.
Originally Posted By: cristiancc
The car is 110k miles. Replaced oil was dark-green but not burnt. Used ZF lifeguard 8 and new pan&filter. I did a software update at the end of 2016.
There is a difference in shift quality some minutes after the engine oil has reached the operating temperature (seeing in the dashboard). This is probably when the transmission oil gets to the right temperature.
But why would it shift bad when the oil is cold and shift better when hot?
In the winter at freezing temps, the 1-2 shifts in the first miles were violent. No sound, just the car reducing speed and then being thrown forward. The 2-3 shifts were better, 3-4 even better to unnoticeable.
During this time I've done some changes: replaced solenoids. Tested both the solenoids and the valve body at a transmission shop - both of them generated on screen graphs that were according to specs, they said. So all normal. Yet, the 1-2 rough shifting is still present, this time harder when warm, but not so harsh as it had been with previous solenoids when cold. Tranny shop suggested replacing components until it gets "fixed".
It's only happening at very light acceleration.
With the transmission adaptions reset, the 1-2 shift is a lot harsher than it was before resetting, while the rest of the shifts are quite smooth.
Checked operating variables for transmission such engine oil & trans temp, air flow, coolant temp, speed, etc, all seem normal.
Transmission fluid was changed two years ago.
The clutch application chart for this transmission shows that when 1-2 shift happens, clutch C gets disengaged and clutch E gets engaged. But these clutches get engaged/disengaged for other gears as well which don't produce a rough shift.
Any advice?
I'm going to assume no codes since you didn't mention that you were getting them.
I wonder if the fluid level is correct. These ZF transmissions require a final fluid measurement at a specific temperature range of 30C - 40C. I wonder if it's under-filled.
https://blog.fcpeuro.com/how-to-service-a-zf-8hp-transmission
My two cents.
No error codes. I've checked the fluid level more than once. Also tried disconnecting MAF, MAP, EGR or oxygen sensor. Didn't see any change without them.
Every shift in a ZF 8 speed is a delicate ballet with the throttle body and the engine timing likely being adjusted. Make sure you consider the easy things, too.
I have heard many a European ZF owner complaining of similar behavior. My 14 RAM has not exhibited this at 80k miles with one fluid and filter change..
Could try a bottle of lubegard red. That stuff seems to work wonders for rough shifts.
Try changing the fluid first, seeing if there any updates from BMW for calibration/firmware and work up from there.
